In switch design, sometimes slot structure is used. In the past design, the number of slots and the line flow from a slot to the main switch board are fixed. In this way, flexibility of bandwidth allocation is limited at the hardware. For example, if a broad bandwidth slot is plugged with a service processing board that has lower requirement of data bandwidth, then bandwidth resource is wasted.
FIG. 1 shows a slot diagram of a switch. There are four slots in total, and each slot is designed with upstream bandwidth 8G. Therefore, each of the four slots can be respectively plugged in a service processing board with upstream bandwidth 8G, for example this service processing board supports 8 gigabit Ethernet. If a Ethernet process board with 3G upstream bandwidth is intended to be plugged in one of the slots, for example this board supports thirty 100M Ethernet, the bandwidth of this slot is wasted. In this case only 3G upstream bandwidth is used, however another 5G upstream bandwidth is wasted.
If using two slots having 4G upstream bandwidth substitutes as one slot of the original four slots with 8G upstream bandwidth, two Ethernet process boards each support a plurality of 100M Ethernets can be plugged in the switch. Nevertheless, there are only three slots are available for service processing board with 8G bandwidth. If a service processing board with 8G bandwidth is plugged in the slot with upstream bandwidth 4G, it will cause 50% service flow to be blocked. In some cases, this design is forbidden.